In recent years, vehicles equipped with a power supply device and using its electric power to drive a motor, such as electric cars, hybrid cars, fuel cell cars, and the like, have been attracting attention as environmentally-friendly cars.
In such a vehicle, employing an externally chargeable configuration has also been under consideration. Japanese Patent Laying-Open No. 8-154307 discloses a hybrid electric car including a battery that is chargeable by external charging means, a drive motor that can drive wheels using electric power from the battery, control means controlling operation of the motor, and an internal combustion engine directly or indirectly used to drive the wheels.
To extend travel distance that can be achieved by charged electric power, it is necessary to increase the capacity of a power storage device. However, increasing the capacity of a power storage device results in an increase in cost and an increase in the weight of a vehicle, leading to bad mileage. Therefore, it is desirable to match the capacity of a battery to a usage pattern of a purchasing user.
Specifically, since travel distance per charge is not necessarily the same for each user of externally chargeable hybrid vehicles, there arises a desire to change the capacity of a mounted battery for each purchasing user. For example, it is conceivable to select optimal battery capacity based on the distance between a home and an office of the user.
However, preparing vehicles with various battery capacities results in an increase in manufacturing cost and difficult manufacturing management. Further, it is more preferable that the capacity of a battery owned by a user can be changed when there is a change in the user's usage environment because of a move, job transfer, or the like.